Considerable interest exists in commercial and governmental facilities to develop a low cost, fully effective, recyclable means for total removal of toxic materials from effluent waste water streams of all types, including agricultural run-off and geothermal brines.
Various ion exchange resins are known to provide a degree of removal of a single group of salt impurities; however, effective total removal of heavy metal ions such as mercury, lead and copper, and of certain anions such as nitrate, has been difficult with ion exchange resins. Additionally, many ion exchange resins, although recyclable, are expensive to produce.
Many effluent waste water streams contain a high degree of particulate matter. When the exchange resin or other removal agent is added to the effluent stream, it becomes comingled with the particulate waste matter. This condition presents problems in reclaiming the removal agent from the effluent stream without also removing large amounts of unwanted particulate matter.
One solution to this problem involves removal of the particulate matter from the waste stream prior to the addition of the toxic substance removal agent. This may be accomplished in small pilot plant operations; however, filtration is not practical for large scale industrial or agricultural operations where significant amounts of particulate matter are present in the effluent streams. Therefore, the exchange resin or removal agent must have properties which render it easily separable from an effluent stream containing silt, clay and other particulate matter.